Apparatus for treating ores



av. 24, 1936. EWART APPARATUS FOR TREATING ORES Filed May 17, 1954 3Sheets-Sheet 1 5% W "ME Nov. 24, 1936. A. EWART APPARATUS FOR TREATINGORES Filed May 17, 1934 3 Sheets-Sheet 2 NOV 24, 1936. EWART 2,061,698

APPARATUS FOR TREATING ORES Filed May 17, 1934 3 Sheets-Sheet 3 PatentedNov. 24, 1936 UNITED STATE PATENT QFFEQE APPARATUS FOR TREATING ORESArchibald Ewart, Chicago, Ill., assignor of onehalf to Ralph M. Welch,Chicago, Ill.

This invention relates to improvements in process of and apparatus fortreating ores to recover the metal content thereof, and one of theobjects of the invention is to reduce the ores. and remove therefromsubstantially all of the arsenic, sulphur, phosphorus and otherconstituents which have a melting or volatizing point within the rangeof the temperature employed, as well as remove other constituents withthe sulphur gas.

A further object of the invention is the treatment by sublimation orpurification of the constituents in the ore and the preliminarytreatment of the same, so that after the sublimable elements have beenremoved, the ore is in a practically red hot condition in very smallparticles, and is then in a suitable condition for further treatment toremove the precious metals, and the remainder is discharged and isseparated into diiferent constituent ores, which latter may be furtherseparately treated, if necessary, and in any suitable or preferredmanner.

A further object is to provide an improved process and apparatus ofhandling and separating comparatively low grade ores, and also theutilization of the sulphur as a gaseous medium for carrying or conveyingother gases or sublimed products, such as arsenic, phosphorus and othercontents.

A further object of the invention is to provide an improved apparatusfor carrying the process into operation, embodying improved means forcarrying or conveying the ores being operated upon through a treating,purifying or sublimation chamber, in a dry condition, and in whichapparatus, should for any reason any portion of the conveying oradvancing mechanism for the ores becomes damaged or interrupted inoperation, the same may be readily repaired without necessitating thedismantling of the entire conveying mechanism.

A further object is to provide an improved apparatus of this characterwhich will be of a simple, durable and compact construction, andefiective and efiicient in operation.

To the attainment of these ends and the accomplishment of other new anduseful objects as will appear, the invention consists in substantiallythe process hereinafter more fully described, and in substantially theconstruction, combination and arrangement of the parts of the apparatusfor carrying this invention into operation, as hereinafter more fullydescribed and claimed and shown in the accompanying drawings in which anapparatus for carrying the invention into operation, is shown.

In the drawings,

Figure 1 is a vertical, longitudinal, sectional view of an apparatus ofthis character with parts omitted and parts broken away.

Figure 2 is a detail side elevation, partly broken away, of a portion ofthe apparatus shown in Figure 1.

Figure 3 is a vertical, sectional view taken on line 3-3, Figure 1, onan enlarged scale.

Figure 4 is an enlarged, detail sectional view of a portion of theamalgamating chamber.

Figure 5 is a top plan view of the parts shown in Figure 1.

Figure 6 is an enlarged vertical sectional view of one of the rotaryseparating chambers.

Figure '7 is a sectional view taken on line ll, Figure 6.

Figure 8 is a detail sectional view taken on line 8-8, Figure 1, on anenlarged scale.

Figure 9 is an enlarged detail perspective view,

through a sublimation or purifying chamber where it is heat treated, thematerial being agitated or turned over a number of times during itspassage through the chamber to insure the freeing or extraction of gasesand various volatiles therefrom.

The gases and volatiles are preferably freed without the presence ofoxygen or air and heated by radiation at about a temperature of 500 F.,the gases being removed from the sublimation chamber preferably bysuction.

As the material is discharged from the sublimation chamber it issubjected to a cold water spray that disintegrates the ores, and thecooled and shattered ore falls into a pit of water and mercury, and iscaused to pass through the mercury, (which latter is preferablycontinuously agitated) by means of a weir or baflle submerged. in themercury, from where it passes into a rotary centrifugal separator toinsure recovering the mercury carried by the ores and the reclaiming ofany precious metals carried into the rotary separator.

The ore is then discharged from the separator on to an agitated slimingor separating table, the heavier metals being deposited through thetable on to a conveyor, while the gangue is discharged from the tableover the end thereof.

A blast of iiuid, such as water or steam may be employed to assist inforcing the ores through the mercury, and if steam is employed it willheat the mercury, rendering it more active to the separation orextraction of the gold and silver content of the ore, the mercuryforming an amalgam therewith.

A suitable apparatus for carrying this process into operation will nowbe described.

The ore to be treated is supplied to a suitable hopper l5 and treated ina dry state and if not in a sufficiently dry state, a drier IE willserve the purpose of further drying the same and from the hopper thematerial will pass through a crusher ET. From the crusher ll thematerial will be fed through a chute it to a pulverizer l9, and ifdesired a blast fan 22 may be provided that discharges into the drierH5.

The pulverizer iii discharges at 2% into a suitable separator 22 and theseparator in turn is provided with a discharge outlet 23 and from whichlatter outlet the material is discharged into a purifying or sublimationchamber.

All of the apparatus above described is of the ordinary and well knownconstruction and the various units of the apparatus may be operated in awell known manner.

The sublimation or purifying chamber constitutes a furnace and may beconstructed of any desired size and consists essentially of an upper orgas receiving chamber 2 3, an intermediate chamber in which the ore ispurified or sublimated and a lower chamber 26 constituting the heatingchamber.

Each of these chambers is of a considerable length and is arranged in aninclined plane, inclining downwardly from the receiving end to thedischarge end.

From the discharge outlet 23 of the separator 22, the ore is dischargedinto a hopper 26 to be delivered to the heating or treating chamber 2a.

The chamber 25 is provided with a bottom 2?, the upper face of which isshaped to form a se- "ies or flight of steps 28, which inclinedownwardly from the hopper 26 to the discharge outlet end EQ and the top36 of the chamber is provided with a series of openings 3! to permit thegases formed in the chamber to pass into the upper or gas chamber 2 1.From this chamber 25 the gases may be withdrawn in any suitable manner,preferably by means of pipes 32, and through medium of a pipe 33 whichmay be connected with any suitable suction or exhaust device so as to beconveyed away for the purpose of future separation.

Windows or sight openings may be provided in the side walls of thechamber 25 for the purpose of inspecting the contents of the chamber.

As the material is discharged from the hopper into the chamber 25, itwill be conveyed through the chamber by means of gravity assisted byconveyors which operate in directions transverse to the length of thechamber. These conveyors consist preferably of scraper members one beingpreferably provided for each of the steps 28. These members arepreferably in the form of a plate, the lower edge of which rests uponthe respective steps .3 and is of a length preferably substantiallyequal or slightly greater than the width of the tread of ne step and. ofa height to extend a considerable distance above the tread of the nextadjacent step. The plate is provided with an opening 36 therethrough anda rod 31 eX- tends through the opening, the external diameter of the rodbeing considerably less than the diameter of the opening so that theplate or element 35 will have a rocking movement with respect to therod. Nuts or collars are secured to the rod on each side of the plateand the collars are spaced from each other for a distance considerablygreater than the thickness of the plate so that as the rod 3? isreciprocated the plate or element 35 will be moved over the tread of therespective step to scrape the material therefrom and deliver the same onto the next adjacent step. The plate has a loose connection with the rodso that it will rock with respect to the rod during its reciprocatingmovement thereby insuring a proper positioning of the plate so as toscrape the material from the step.

As before indicated, one of these plates or scraper elements is providedfor each of the steps and the alternate rods Ell are connected on oneside of the chamber 25 by means of a rod or bar (see particularly Figure5) while the other alternate rods 3? may be connected on the other sideof the chamber by a bar or red 20 so that the alternate rods will besimultaneously moved in the opposite directions.

To accomplish this there may be provided a shaft ii journaled insuitable bearings Crank arms d3 are secured to the shaft and links icon-- nect the respective crank arms with the bar or rod 5%.

Similarly a shaft 55 journaled in suitable bearings 56 is provided onthe other side of the machine, and this shaft 55 has crank arms i'lsecured thereto and the crank arms 4? are connected by means of links'18 to the bar or rod li'l.

Motion may be imparted to the shafts =i-s5 in any suitable manner suchas by means of a motor 38, the shaft of which is connected by means of abelt 55 with a pulley l that is secured to a shaft 52 (see Figure 8).Pulleys 53-54 are secured to the shaft 52 and belts 5Ei56 passrespectively over the pulleys 53--54i and also over pulleys 5'i--58respectively secured to the shafts l54i. Thus, it will be manifest thatwhen the shafts li-i5 are rotated a reciprocating movement will beimparted to the scraper plates and the alternate plates will bereciprocated in opposite directions.

The chamber 26 forms the heating chamber and at the lower end thereofthere is provided one or more openings 59 (see particularly Figure 1) sothat the flame from burners or nozzles ii will be directed into thechamber and the products of combustion, owing to the fact that thechamber 2 5 is inclined upwardly, will flow beneath and in contact withthe bottom of the chamber 525 to be discharged into a chimney 65 (seeFigure 5).

If desired and in order to retard the flow of th products of combustionout of the chamber and into the chimney, baflie plates or walls may beprovide so as to retard the flow thereof, and at the same time maintainthe chamber at the entrance end thereof at a high temperature.

As the material flows through the or let it? from the chamber it will bedischarged into a chamber in which mercury ii i provided and theprecious metals will be separated from the gangue in the chamber 63. Thechamber may be of any desired depth according to the amount of mercurydesired to be used, and a bafile or weir B5 is provided with one endthereof submerged into the mercury so as to force the products from thechamber 25 through the mercury before it will enter the chamber 66.

Arranged to operate in the chamber 63 and in advance of the weir orbaffle 65 is an agitator 6'! which is connected with a rod 68 and isadapted to be reciprocated so as to move up and down within the mercuryto agitate the same and to assistin forcing the material from thechamber 25 through the memory. This agitator may be operated in anydesired or suitable-manner, and the upper face thereof is preferablyinclined as at 69 so as to assist in shedding any of the material whichmay pass on to the upper side thereof.

As a means for assisting in cooling the hot product as it comes from thechamber 25 and for breaking down the product by disintegrating the same,it is subjected to the action of a cold spray of water from a pipe iii,and if desired a baffle ll may be provided against which the waterstrikes.

a This spray may be in the form of any other fluid if desired and ifsteam is used it will assist in heating the mercury to keep the same ina condition which will result in a ready action thereof upon the ores orproducts passing therethrough.

If desired and in order to cool the product as it enters the chamber 63,suitable blast fans 12 may be provided for directing a current of coldair into the chamber.

The chamber fili may be of any desired length and the bottom thereof iscorrugated or undulated as at F3 for the purpose of confining any of theheavier particles which will be separated from the liquid as it flowsthrough the chamber 86. The bottom of the chamber 66 is inclined fromthe inlet to the outlet end and the material may be discharged from thechamber 66 through one or the other of discharge outlet openings lll'5.

The numeral. l5 designates generally a rotary separator mounted torotate upon a horizontal axis and are provided for the purpose ofseparating the precious metals if any should escape from the amalgambath.

In the present form of the invention two of these separators aredisclosed, one being connected with each of the outlet openings i lib ofthe chambers 16 and as the construction and operation of each of theseseparators is the same, the description of one will apply equally aswell to both of them.

The separator is provided with a circular body portion having an inletopening l'i'. The opposite end of the body is preferably tapered orconical as at E3, and connected with the apex of the conical portion isa tubular extension it. The separator is supported preferably by meansof a yoke 8d, the arms 8l--82 of which form bearings respectively forthe tubular ends 79 and ill and these separators may be rotated in anysuitable manner, such as by means of a belt 83 passing over the bodyportion of the separator and also over a pulley ti l secured to a shaft85. The shaft 35 is provided with a pulley 86 over which a belt 8?passes, and this belt in turn passes over another pulley 88 secured tothe shaft ll so that motion will be imparted to the shaft from the shaftii. A clutch device s9 is provided in the shaft 85 and an actuatinglever 9i) controls the clutch.

Thus it will be manifest that either one or both of the separators 715may be rotated by rendering active or inactive the respective clutchdevices 8Q.

The chamber $6 is provided with a gate 9i (see particularly Figure 5)adapted to be positioned so as to out 01f the outlet opening l4 anddirect the material through the outlet it? as shown in Figure 5 in fulllines. The gate 9i, however, may be positioned as shown in dotted linesin Figure 5, so as to direct the products through the outlet openings il and prevent their flowing out of the outlet '45.

In this form of the invention the gate 9| is a sliding gate adapted tobe positioned into co-operating guides er.

Each of the separators i5 is of sectional construction (see particularlyFigure 7) comprising a body portion 83 and a removable section 94 heldtogether in any sui able manner. A lining comprising sections 95 isprovided for the body portion of the separator, and these sections 95are preferably in the form of plates constructed of copper or any othersuitable material which has an aflinity for mercury or amalgam, so thatin the event any of the mercury is carried by the product into theseparator it, it will be picked up or will adhere to the plates orsections 95.

These plates 95 are secured together in any suitable manner, preferablyby means of sockets 96 along one edge of the plates, and a shouldered orrounded portion er along the other edge of the plates, and whichportions 97% are adapted to be sprung into the sockets 96 so as tod-etachably secure the sections together.

Anchor bolts 98 may also be provided, which pass through the respectiveplates and through the body portion of the separator to hold the platesin position.

When it is desired to remove the plates 95, the section. of the body ofthe separator is removed after the bolts 98 have been loosened. One ofthe plate sections 95 may then be removed by springing the endsthereofout of locking engagement with the next adjacent plates and thenthe remaining section of the plate may be removed.

Agitators or wings 99 are secured within the body portion and aresuitably supported, the ends of the agitators extending into the conicalend of the body portion. These wings or agitators are spaced from thewalls of the body so as not to interfere with the insertion or removalof the plates 95.

Thus it will be seen that when the material is discharged from thechamber 66 into one or ,the other of the separators it, when the latteris rotated, centrifugal force will throw the heavy particles outwardlyagainst the plates 95 and any amalgamated metal in the separator it willadhere to the plates 95 and may be recovered after the plates have beenremoved.

From the separators it the material is discharged upon a separator orslirning table 586, which is preferably inclined and is adapted to begiven an endwise vibration by mean of a crank shaft ltl having cranksuse, and the cranks are connected by means of links it? with the tableso that when the shaft ldl is rotated an endwise vibration will beimparted to the table, with the result that all of the metals whichremain after the precious metals have been separated will be separatedupon the table liiil. The shaft iii! may be rotated in any suitablemanner such as by means of a belt passing over a pulley H15 on the shaftand also over a pulley lilii on the shaft 52.

he top of the table is provided with downwardly projecting V-shapcdgrooves iii? in the bottom of which grooves are arranged a series ofopenings ifilil that extend entirely through the top of the table, andbeneath the top is arranged an endless conveyor 6E9 which may be givenmotion in any suitable manner such as by means of a pulley i id, overwhich a belt from any suitable source, may pass, and which pulley isconnected with the shaft 5 i i and on which shaft is mounted a rollerH2, over which the endless conveyor passes.

The discharge end" ject for any suitable cistance, but are not longenough to prevent the separator chambers 16 from being tilted in thedirection of their longitudinal These separator chambers are preferablymounted so that they may be tilted when it is desired to drain out anyof the liquid which might be confined within the chambers, owing to theconical ends 'EB.

In order to accomplish this tilting the yokes 89 are mount upon astandard H3 and are connected thereto by means of pivots l The pipes illi which rm connections between the respective inlet end l? of therespective separators it with the respective discharge outlets 'MTi ofthe chain are of flexible material and are surhci t length so that thetilting of the separators i l will not be interfered with u. r is of asufficient length so as to permit a flow of the material therethroughwhich will be sufficient to permit the ieavier elements to beprecipitated and retained within the between the riiiies or corrugationson the bottom of the chamber (56.

During the treatment of the material in the purifying or sublimationchamber the process is carried on without the admission of air.

It will be manifest that in the operation of the device the actuation ofthe scrapers or conveyors will cause the material to be gradually feddownwardly along the steps or the bottom of the sublimation chamber tothe discharge end thereof, and the operation of these blades in thusscraping or moving the material from one step to the next lower stepwill cause the material to be thoroughly agitated and turned over agreat many times so as to insure and assist in the extraction or removalof the gases therefrom, the ore concentrate being turned over and movedfrom side to side of the chamber a great many times during its travelfrom the intake to the discharge outlet thereof. This effects thepresentation of almost a continuous new surface of the ore concentrateto the applied radiated heat at all times.

The continual agitation of the ore and its passage or movement down andacross the bottom of chamber in. addition to the presentation of newsurfaces will result in the surface continuously giving cii vapors andalso prevents melting of the metal contained in the ore, which formationwould prevent further vaporization.

By reason of the fact that there will be little or no air present in thesublimation chamber, there will be little if any oxidizing action,either as to the ore or as to the sulphur or arsenic and the likeconstituents.

Obviously, the suction pump may be operated during desired intervals, orcontinuously.

If any steam resulting from the spray from the pipes it should enter thesublimation chamber in the form of super-heated steam, it will be forcedupwardly in the chamber towards the intake end and the sulphurous gasesand vapors as well as the other vapors will immediately follow thismovement, the vacuum or suction creating device operating to draw on"the vapors.

The ore which reaches the end of the bottom of it of the separator isprothe chamber 25 or the outlet 29 of the chamber will be in apractically red hot condition and still in particle form. If there isany bonding between the particles due to some peculiarity in theparicular ore or some localized heat condition, the ore will be brokenup by dropping into the pit or chamber 63 where it is contacted with thedischarge jets of cold water, and which discharge is continuous. Thewater will flow from the chamber 53 into the chamber 56, leaving onlythe metallic content of the ore or the relatively pure metals and thesecollect in the chamber 63 and work their way down beneath the submergedend of the weir or baffle 65 to enter the chamber 66.

In the process the material in a relatively fine, pulverized and dryform is fed in a relatively thin, fiat sheet along the steps or bottomof the sublimation chamber and is advanced and agitated and turned soall of the dry pulp particles are turned over and over. This permits thevarious volatiles in the pulp to be freed therefrom and this freeingoccurs by reason of the employment of heat of a radiating or radiantcharacter, preferably without the presence of oxygen or air. Thetemperature employed is governed by the nature or the material beingtreated, but is sufficient to substantially free the ore from all of itssulphuric, rsenic, antimony and phosphorus constituents and these aresuitably removed from the sublimation chamber by applying suction.

The process which has been heretofore set forth and more or lessspecifically described in the description of the operation of theapparatus is what might be termed a dry separation process; that is, itis not a smelting process but is a sublimation process.

It its in the production of practically pure metal in their separateforms and this is possible,

befor stated, by breaking down of the complex ores, usually sulphur andarsenic combinations, by sublimation of the sulphur and arsenic and theprevention of oxidation and the prevention of smelting.

An inherent character of this process is that it is essentially a dryprocess and it can handle on a profitable basis ore that is nowrelatively unprofitable because it recovers as end products the variousrecovered constituents in substantial 1y final form and with a minimumof heat and power consumption.

The treatment of the ore after it passes from the end of the sublimationchamber, separates the amalgamated metals and minerals from the gangueand reduces them in raw state, whereby all of the metals may bereclaimed after smelting. The fineness of the ore, the exacttemperature, and the rate of ore travel important factors in the dryproduction of the ore. The crusher first reduces he ore to a finenessfor drying and for the pulve o fur operate upon.

While the 1 red process has been herein described and the referred formof apparatus for carrying the process into operation has been also shownand specifically described, is to be understood that various changes maybe made in the steps of the process and in the construction, combinationand arrangem nt of the several parts of the apparatus, within is scopeof the claims, without departing from the spirit of this invention.

is claimec. as new is:-

l. An apparatus ror treating dry and finely divided ore, comprising an.inclined chamber through which the ore has a general direction of flowby gravity, means for heating the chamber, means for agitating the oreas it advances through the chamber, the last said means operatingtransversely to the general line of travel of the ore through thechamber, and means for confining and drawing ofi the vapors from theore.

2. An apparatus for treating dry and finely divided ore, comprising achamber through which the ore is conveyed, a table in the chamber overwhich the ore passes in a general direction from one end to the otherend thereof, means for heating the chamber, means for agitating the oreas it advances across the table, the last said means operatingtransversely to the general line or travel of the ore across the table,and means for confining and drawing off the vapors from the ore, the oreengaging surface of said table being shaped to form a flight of steps,the tread of each step being of substantial width and length.

3. An apparatus for treating dry and finely divided ore, comprising anelongated chamber through which th ore passes, a table in the chamberacross which the ore advances in a gencral direction from one end to theother end thereof, means for heating the chamber, the ore engagingsurface of the said table being shaped to form a flight of steps thetreads of which steps are of substantial width and length, scraperscontacting with and movable over said treads in directions transverse tothe general direction of travel of the ore across the table, and meansfor confining and conveying the vapor from said chamber.

4. An apparatus for treating dry and finely divided ore, comprising anelongated chamber through which the ore passes, a table in the chamberacross which the ore advances in a general direction from one end to theother end thereof, means for heating the chamber, the ore engagingsurface of the said table being shaped to form a flight of steps thetreads of which steps are of substantial width and length, scraperscontacting with and movable over said treads in directions transverse tothe general direction of travel of the ore across the table, and meansfor confining and conveying the vapor from said chamber, alternatescrapers operating in opposite directions.

5. An apparatus for treating dry and finely divided ore, comprising anelongated chamber through which the ore passes, a table in the chamberacross which the ore passes in a general direction from one end to theother end thereof, means for heating the chamber, the ore engagingsurface of the said table being shaped to form a flight of steps thetreads of which steps are of substantial width and length, scraperscontacting with and movable over said treads in directions transverse tothe general direction of travel of the ore across the table, means forconfining and conveying the vapor from said chamber, each of saidscrapers comprising a plate like element disposed on one edge, anactuator therefor, and means connecting the scraper to the actuator forbodily movement therewith and for free lateral movements with respectthereto in directions lengthwise of the actuator.

6. In an apparatus for treating ore, a table over which the ore passesin a general direction from one end to the other end, and means formoving the ore backwards and forwards and in directions transverse tothe general direction of flow across the table and for turning the oreas it advances, the said means embodying an operating member, a scrapermember through which the operating member loosely passes, stops securedto the operating member on opposite sides of and spaced from the scrapermember whereby the scraper member will move independently of theactuating member as the latter is reciprocated, and means forreciprocating the operating member.

'7. In an apparatus for treating ore, a table over which the ore passesin a general direction from one end to the other end, means for movingthe ore backwards and forwards and directions transverse to the generaldirection of flow across the table and for turning the ore as itadvances, the said means embodying an operating member, a scraper memberthrough which the operating member loosely passes, stops secured to theoperating member on opposite sides of and spaced from the scraper memberwhereby the scraper member will move independently of the actuatingmember as the latter is reciprocate d, and means for reciprocating theoperating member, said table comprising steps upon which the ore ismoved by the scraper, said scraper being individual to the steps.

8. A treating table for ore, said table being inclined to cause the oreto flow thereover, and

scrapers for agitating and turning the ore as it passes over the table,said scrapers operating in directions'transverse to the direction offiow of the ore over the table, said scrapers embodying a scraperelement arranged on edge, and an actuating member connected to thescraper, said connection embodying means permitting the scrapers to rocklaterally and with respect to the actuating member as the latter isreciprocated.

9. A treating table for ore, said table being inclined to cause the oreto flow thereover, and scrapers for agitating and turning the ore as itpasses over the table, said scrapers operating in directions transverseto the direction of flow of the ore over the table, said scrapersembodying a scraper element arranged on edge and an actuating memberconnected to the scraper, said connection embodying means permitting thescrapers to rock laterally and with respect to the actuating member asthe latter is reciprocated, said table being stepped and said scrapersbeing individual to the steps.

10. An apparatus for treating dry and finely divided ore, comprising achamber through which the ore is conveyed, an inclined table in thechamber over which the ore has a general direction of flow by gravity,means for circulating a heating medium through the chamber beneath saidtable, means for agitating the ore as it advances through the chamber,the last said means operating transversely to the general direction offlow of the ore over said table, a chamber disposed above and extendingsubstantially from one end to the other end of the table and havingopenings for receiving vapors from the ore, and means for conveying awaythe vapors from the last said chamber.

11. An apparatus for treating dry and finely divided ore, comprising aninclined chamber through which the ore has a general direction of flowby gravity, means for heating the chamber, means for agitating the oreas it advances through the chamber, the last said means operatingtransversely to the general line of travel of the ore through thechamber, means for confining and drawing off the vapors from the ore, anamalgamator receiving the ore from said chamber, and a separatorreceiving the ore from the amalgamator.

12. An apparatus for treating dry and finely divided ore, comprising achamber through which it advances over the table, the last said meansthe ore is conveyed, a table in said chamber, said Operatingtransversely t0 the general line table being inclined in a generaldirection from travel of the ore over the table, and means for one endto the other end of the chamber, and confining and drawing off thevapors from the over which table the ore passes, means for heatore. 5ing the chamber, means for agitating the ore as ARCI-IIBALD EWART.

